On the centre of two-parameter quantum groups Ur,s(g) for type Bn with n even

The paper mainly considers the centre of two-parameter quantum groups Ur,s(so2n+1) via an analogue of the Harish-Chandra homomorphism. When n is even, the Harish-Chandra homomorphism is injective and the centre of two-parameter quantum groups Ur,s(so2n+1) is described in the sense of the Harish-Chandra isomorphism based on the Rosso form and the weight module representation theory established in Bergeron-Gao-Hu (2007).